The 1920’s Shur-Stop Glass Fire Grenade could be thrown at the fire or suspended, with a bracket assembly, directly over areas of particular fire risk, like boilers and furnaces. If high temperatures reach some styles of brackets, it would release the grenade that would then crash and shatter, releasing the fire suppression liquid. The liquid in the clear glass often had a blue or red coloring agent. In the more recent grenades, a fire suppression chemical is likely to be present instead of the salt water.
The chemical of choice was carbon tetrachloride (CTC), which can be really unhealthy if inhaled, ingested or absorbed. Even worse, when this chemical is exposed to the heat of a fire, it can produce phosgene gas, a chemical weapon used in WWI.
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